Merge branch 'release/0.2.1.0' into develop
initial Data.Identifiers.ListLike implementation.
updated benchmarks.
Fixed ListLike property tests by allowing the TrieMap to assign a value to an empty key.  Also, introduced new implementation of the TrieMap that is much more memory effecient than the previous version.
Further reduce space requirements of Data.Identifiers.ListLike with ValueEnd constructor that takes no 'nodes' list.
Merge branch 'feature/listlike' into develop
removed unused benchmark.
bumped version number
Merge branch 'release/0.3'